This invention relates to the field of display devices and particularly to the methods and apparatus for the improvement of color and spatial discrimination of pictorial images for viewers with vision impairment.
At present, when a person wants to view a photographic print he simply picks it up and looks at it. However, a person with a visual impairment cannot fully participate in the pleasure of photography due to their lack of visual acuity. The visual shortcomings of these people are partially addressed in U.S. Pat. No. 5,267,331 by Siwoff issued Nov. 30, 1993, entitled Digitally Enhanced Imager for the Visually Impaired, wherein a device is described which scans a page of text and creates a high resolution, high contrast image which is displayed upon a high resolution monitor. This enhancement of text eliminates any xe2x80x9cgrayxe2x80x9d transitions between the text and the background thereby improving resolution. However this process is not applied to pictorial images because it does not improve the appearance of the pictorial image for a person with visual impairment. Also, U.S. Pat. No. 5,467,123 issued Nov. 14, 1995 to Zeevi et al., entitled Apparatus and Method for Enhancing Color Images discloses a color image apparatus comprising apparatus for receiving signals representing a color image, image processing apparatus, and display device for displaying the processed signal. The image signal is processed to improve the appearance of the image for viewers who are color blind. The image processing extracts information that cannot be detected by the user (ex. yellow-blue signals) and adds the extracted information to a channel the user can detect (ex. red-green) thus enhancing their visual discrimination. This approach renders an image that appears extremely unnatural to any viewer, including a viewer that is color blind. There is a need, therefore, for an improved method and apparatus for displaying pictorial images to individuals who have impaired color and/or spatial discrimination.
The present invention meets the need by providing a method for displaying a digital color image to a visually impaired person that includes the steps of: measuring the visual response of the person and specifying a set of enhancement profiles relating to the person""s color and spatial frequency visual perception, adjusting the color content of the digital color image in response to a color content enhancement profile; adjusting the spatial frequency content of the image in response to a spatial frequency profile; adjusting the contrast of the image in response to a contrast adjustment profile; and displaying the adjusted digital image to the person.
This method and display apparatus, which will be explained in full detail below, enables a visually impaired person to take any image, whether digital or hardcopy, enhance that image according to a measured profile, and output that image to either a monitor or a hard copy output device. This method has a distinct cost and logistical advantage. Rather than producing customized output such as photographs for each visually impaired person, the photograph is simply placed into a reader and either viewed or printed out. Additionally, when compared to the image processing disclosed in U.S. Pat. No. 5,467,123, the present invention produces a more natural looking image with enhanced discrimination.